It is by now common knowledge that stress in mammalian subjects develops directly or indirectly into a display of oxygenated activities that quickly changes the usual reduced state of the body. This hyperoxygenated state--with resulting hydroxides, peroxides and related free radical states--can cause great physical imbalance and actual physical damage that can change pathological states, which in turn develop into atherosclerotic plaques. Such plaques can result in the deposition of high lipid levels particularly in a blockage of arteries that can cause a cessation of blood flow to the heart with a resulting heart attack. This is one of but many human disease states that are caused by free radical attack from the hyperoxygenated state caused by stress. What is not appreciated what markers can be utilized to measure oxidative stress.
Malondialdehyde is a component of normal urine. Its presence can be determined quantitatively using equipment such as spectrophotometers, fluorometers, high performance liquid chromatographs and gas chromatograph mass spectrometers. In another method applicable to aldehydes in general, (disclosed at page 395 in "Qualitative Analysis by Spot Tests", Third Edition, authored by F. Feigl and published by Elsevier Publishing Company, Inc.), a drop of sample solution which may contain aldehyde is mixed with 2 ml of 72 percent sulfuric acid in a test tube. A small amount of solid chromatropic acid (1,8-dihydrooxynapthlanene-3,6 disulfate) is added and the test tube is heated in a 60?C water bath for about ten minutes. A bright violet color appears in the presence of aldehyde; sensitivity of the test is reportedly about 3 ppm of aldehyde.
In yet another method generally applicable to aldehydes, described at pages 339-340 of the Feigl publication, a drop of aqueous (or alcoholic) solution suspected of containing an aldehyde is treated on a spot plate with a drop of sulfurous acid and a drop of fuchsin/sulfuric acid and allowed to stand. A red to blue color appears within about two to thirty minutes, according to the amount of aldehyde present in the test solution being tested. Such test is reportedly sensitive to about one microgram of formaldehyde in the drop of solution being tested. The problem with such a test, and other known aldehyde tests, is that the tests are not quickly and easily performed. The first above-described test, for example, requires heating of a test tube of solution in a constant temperature water bath for ten minutes.
Despite the prior existence of these tests, it has never been appreciated that such tests can be applied to malondialdehyde in urine to detect oxidative stress Thus, there is still a need to provide methods and apparatus for detecting oxidative stress in subjects.